Many types of electronic devices are designed to be worn by a user. Examples of such devices include headsets, headphones, microphones, etc. In some applications it is desirable to know or detect whether the device is being worn (i.e., “donned” or “DON'd”) or not worn (i.e., “doffed” or “DOFF'd”).
Various types of sensors have been proposed for detecting whether a device is being worn. In headset devices, for example, a sensor based on a mechanical switch is typically used. FIG. 1A (headset operational) and FIG. 1B (headset non-operational) are side-view drawings of a monaural type headset equipped with such a mechanical switch (in this case normally-open). The headset 100 comprises an ear piece 102 and a microphone boom 104 containing a mechanical switch 106. The ear piece 102 is connected to the microphone boom 104 at a pivot, which is not shown, allowing the microphone boom 104 to be rotated upwards (counter-clockwise in the side view of FIG. 1A). In FIG. 1A the mechanical switch 106 is open, indicating that the headset 100 is in the DON'd state. In FIG. 1B, which shows the same side view of the headset 100 when the microphone boom 104 has been rotated upwards, the mechanical switch 106 makes contact with the inner portion of the ear piece 102, indicating that the headset 100 is in a DOFF'd state.
Although DON/DOFF sensors based on mechanical switches can be used to detect the DON'd and DOFF'd states of a device, they are susceptible to false triggering. For example, if the device is placed in a handbag or briefcase while not in use, other items in the handbag or briefcase may inadvertently trigger the mechanical switch. Other types of DON/DOFF sensors are also susceptible to false triggering and/or have other drawbacks. It would be desirable, therefore, to have a DON/DOFF sensor for devices worn by a use that avoids false triggering and other drawbacks of prior art DON/DOFF sensors.